The necessity for removing oil and non-condensible gases for maximum efficiency of refrigeration systems has long been recognized, and many proposals, including my U.S. Pat. Nos. 2,149,358, 3,534,564, and 3,837,175, have been advanced. Oil lubricated compressors are a conventional part of commercial refrigeration systems and are the source of the oil that reduces the heat transfer coefficient. Conventional traps collect the oil droplets in the hot gas and return the oil to the compressor. Our method of desuperheating the gas before passing through slanted apertured baffles with zig-zag flow pattern causes the cooled oil mist to coalesce and collect on surfaces, and the foam bubbles are ruptured by the sharp edges of the baffles; the oil droplets gravitate down the stationary baffle structure into the oil trap to be continuously returned to the compressor at reduced pressure, after heating to remove the saturated gas and vaporize any liquid present before the oil enters the compressor crankcase, to minimize foaming.
Our Desuperheater & Separator units with direct contact cooling now operating in a number of ammonia refrigeration plants are collecting substantial amounts of oil from the hot gas that passes through the conventional type traps as mist and foam with the hot gas. The indirect contact cooling by flashing liquid refrigeratant at condenser pressure is applicable for desuperheating the various evaporative refrigerant gases, miscible or immiscible with oil, as the liquid does not contact the oil when a conventional type heat exchanger is used with the hot gas contaminated with oil flowing through the tubes of the heat exchanger. The tubes are surrounded with liquid refrigerant at the condenser pressure causing the liquid to flash to gas (vaporize) as the hot contaminated gas is cooled.
The cooled mixture of gas and oil is forced from the heat exchanger into our Oil Mist Separator-Collector (OMSC Unit) constructed very much like our Desuperheater & Separator unit with stationary slanted baffles where the bubbles are ruptured and the cooled oil mist coalesces and collects on the surfaces and flows into the oil trap to be returned to the compressor. The clean cooled gas is forced into the condenser; the heat transfer coefficient is improved by removing the oil before the gas enters the condenser. Also the coefficient is much higher when condensing gas than it is when cooling gas, which reduces the head pressure required to condense the gas and saves power to operate the compressor. The clean liquid gravitates from the condenser with non-entrainment trap, for collecting the non-condensible gases, into a standard receiver with our non-agitating inlet connection to minimize agitation of any oil in the receiver. This permits draining oil from the receiver during operation when ammonia is the refrigerant; the oil settles to the bottom of the vessel.